a. Field of Invention
The invention relates to a sampling device for the removal of filtered samples from fluids comprising a container including a rotatable agitor above a filter membrane, an inlet ending in the container above the filter membrane and a filtrate outlet for the discharge out of the container beneath the filter membrane.
b. Description of the Prior Art
There have been known agitator cells comprising a magnetic stirring rod pendingly mounted above a filter membrane (AMICON magnetic stirrer cell). The filter membrane rests on a plate having profiles on its surface to evacuate the filtrate. The fluid to be filtered is introduced under pressure through a cover inlet into the container and, by the magnetic stirring rod above the filter membrane, it is kept in movement.
For chemical, in particular biochmeical process technics, there is an ever increasing demand of on-line measuring methods to determine chemical substance parameters in process for monitoring, regulating and controlling purposes and the time between the samping step and the availability of the result should be as short as possible. As a rule, the following four steps are required for performing on-line-analysis:
1. sampling by branching off a representative partial current, PA1 2. preparing the sample (e.g. removing solids or interfering accompanying substances) PA1 3. analytic determination (detection process) PA1 4. evaluation (registration).
The first two partial steps are frequently involved with considerable difficulties if a quick time behavior is required.
As a rule, only a discontinuous sampling of dissolved or gaseous low-molecular components may be effected with the known sampling means. For the representative removal of macromolecules such as proteins and enzymes, the existing systems are unsuited because of occurring phenomena of denaturation and non-controllable coating and clogging problems. Basically, unfavorable long dead times are inherent to dialysis systems because the concentration difference required for the material transport is to be taken into consideration.
In biotechnology, use is made of by-pass systems in a closed cycle, in order to perform for instance a continuous fermentation with cell mass retention for the harvest of cells and for the processing of bio-products. Due to the membrane fouling by adsorption and polarization effects, the use of such techniques or technic is critical for continuous sampling. Further problems result from the normally high dead volumes with respective long response times and by the short service lives.